Thiocyanates of 2-vinylthiophenes



thiocyanate groups.

Patented Sept. 30. 1952 William s. Emerson and Tray -M. IPati-ick, Jr'., Dayton, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Dela- No Drawingn Application-July; 1; '1947,

Serial No. 758,474 a V 7 Claims. (01. 260 -329) The present invention relates to a new class of "compounds. namely thiocyanates of 2-vinylthiophene'st v v The new compounds of this invention possess structure. A oH--oH I u -1 any ac C-CH:

where It represents halogen or hydrogen and X and ,Y represent thiocyanate or-isothiocyanate groups. When R is halogen, it is intended to include 'either'fluorine, chlorine, bromine or iodine.

The above new compounds may be prepared by reacting 2-vin'ylthiophenes with thiocyanogen in an inert anhydrous non-polar organicsolvent. However, the method for producing styrene dithiocyanate described in U. S. Patent 1,790,097 to Kaufmann is not generally applicable to the vinylthiophenes. Treatmentiof 2-vinylthiophene y with bromine and an alkali metal thiocyanate'in glacial acetic acid produced a product which gave negative tests for both the thiocyanate or :iso- The -5-chloro-2-vinylthiophene produced only a small yield of the dithiocyanate. the principal product being a compound which gave no test for either the thiocyanateor the isothiocyanate groups. On the other hand,

- 5,-b romo=2-vinylthiophene dithiocyanate may be "prepared in this manneralth'ough a higheryield was obtained by reacting 5-bromo-2-vinylthiophene with. thiocyanog'en in anfinert anhydrous non-polar solvent. 1A8 suitable 'non 'polar solven'ts mention maybe made of benzene, toluene,

xylene, carbon tetrachloride, ethyl ether, butyl ether, petroleum fractions such as ligroin; chlorinated petroleum fractions andgequiv'alents and analogues thereof. The following examples are specific em ddiments of the invention and are tone as illustrative, not limitative thereof. I

Z-vinylthzophene dithiocuanate A solution of thiocyanogen. in dry benzene Fwas prepared by treating an ice cold suspension of 194 grams of lead thiocyanate in 300cc. of benzene with a cold solution of SO-grams of bromine in 300 cc. of benzine. The solid was separated by filtration and washed with 150 cc. of benzene. Fifty-five grams of z-vinylthiophene was added to the filtrate and the solution was allowed to stand all day in the bright sunlight. It was then seeded and placed in an ice box overnight. The first crop of crystals was separated by filtration and the filtrate was evaporated under reduced pressure at room temperature to" a 'thickfsyrup. Additional product was filtered from-this syrup. The total yield of crude 2'-vinylthiophe ne dithi ocyanate' was 64 grams (57%). anal yti'cal sample was crystallized four -time's-- by--dissolving -inbenzene and precipitating with hexane, M. P. 87 C.- Y 1 Anal. Calculated for CaHsNgSa; N; 12.4 Found: N,12 3 1'. A, 1".. This compound gave the blood red color char- "acteristic of a'positive test for the thioeyanate boiled for three to five minutes with 10% aqueous sodium hydroxide, the mixture"cooki -acidified with dilute sulfuric acid and a small amount-of 1% ferric chloride added (Wood,"-".Organic ReactionsflJohn Wiley and Sons, Inc.,-New Yor-k,

'1946, vol. III, p. 254) It'I'gaVe -a negativetest for the presence "of' isothiocyanate'*(Mulliken, Identification of Pure 'Organic'Cor'npourids', John Wiley. and Sons, Inc.', New York l922,=' vel. IV, p. 18); This test is carried out by shaking a small amount of the solid with aqueous ammoni- -'acal silver nitrate, heating if necessary. :A-bla'ck precipitate,which was not obtainedlwith vinylthiophene dithlocyanate, constitutes a-po'sitive test. V .I.

EXAMPLE 11" 5 -chZoro 2winylthiophfie dithiocyanute I This compound was prepared 'thepreeedur'e described in Example'I. 50.6 grams of 5-chloro- 2 -vinylthiophene was added to a solution ofthiocyanogen in dry benzene made froml'l25granis of lead thiocyanate in 250 cc. of '-anhydrous1benache and 5 6gramsof bromine1in 3001cc. cilanhydrous benzene. The' initialpreclpitate'igand that obtained by diluting the-filtrate withhexane weighed 47.5 grams, MQ P. 97-98" 'C.",'and"con'- stituted a 52% yield of 5-chloro-2-vinylthlophene dithiocyanate. An analytical"'sainple *i:nelted at 99 C. after two crystallizations from benzenehexane.

Anal. Calculated for C8H5N2S3C1Z C, 36.9; H, 1.93. Found: C, 36.8; H, 1.89.

5-chloro-2-vinylthiophene dithiocyanate gave a positive test for thiocyanate and a negative test iorisothiocyanate. l

. .The 1 5-fluoro-2-vinylthiophene i dithioc-yariate may be prepared by a similar procedure.

EXAMPLE III s -chloro-za-isothiocz/anmp-thiocyanoethyl) thiophene The filtrate from Example II obtained by diluting the benzene solution with hexane and lil- 

1. A COMPOUND OF THE STRUCTURE 